fix: Cast to FrameworkElement/Window when accessing Loading/Activated to avoid issues when shadowing

[Youssef1313]

GitHub Issue (If applicable): closes #18020

PR Type

What kind of change does this PR introduce?

What is the current behavior?

What is the new behavior?

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• [ ] Docs have been added/updated which fit documentation template (for bug fixes / features)
• [ ] Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
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• [ ] Contains NO breaking changes
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Other information

Internal Issue (If applicable):

[unodevops]

🤖 Your WebAssembly Sample App stage site is ready! Visit it here: https://unowasmprstaging.z20.web.core.windows.net/pr-18051/index.html

[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-18051/index.html

[unodevops]

🤖 Your WebAssembly Sample App stage site is ready! Visit it here: https://unowasmprstaging.z20.web.core.windows.net/pr-18051/index.html

[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-18051/index.html

[yeahg-dev]

@jeromelaban If It's not a problem, Could you backport this changes to latest version?

[MartinZikmund]

@mergifyio backport release/stable/5.3

[mergify[bot]]

backport release/stable/5.3

✅ Backports have been created

• #18082 fix: Cast to FrameworkElement/Window when accessing Loading/Activated to avoid issues when shadowing (backport #18051) has been created for branch release/stable/5.3 but encountered conflicts

[xperiandri]

Was it released to 5.3.108? I still experience the error

[Youssef1313]

No, it's not available in that version. cc @jeromelaban